Cooling apparatus



Aug. `163, 1938. s. H. MacGRl-:GOR

COOLING APPARATUS vFiled March 2, 1938 Inventur- 5tEp hE1LH-MacBrE nr'Attnrma "mwuvu uw A W, A w Q mm .v m E, 4 .///dhhrmmhhhnnswWn-..EHQUE r:LI l* Y m b W/:WMNMMSMQM I.,I. r m `N QN mm w N. m .n Q ""nmmh Y h NN QN [Y m YN l .H I mlm mw 'Patented Aug. 16, 193s UNITED STATES PATENTOFFICE 3 Claims.

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) 'I'he invention described hereinmay be manufactured and used by or for the Goverment for governmentalpurposes, without the payment to me of any royalty thereon.

This invention relates to a cooling apparatus.

'I'he general purpose of the invention is to provide an apparatus inwhich cooling is accomplished by expansion of a compressed gas. Moreparticularly the invention resides in an arrangement of cylindersdisposed coneentrically about a member to be cooled and providing rstlyfor expansion of the gas in an outer chamber, secondly for heating andrecompression of the gas in an inner chamber where the gas is in contactwith the member to be cooled, and thirdly for expansion of the gas intoan intermediate chamber.

A further object of the invention is Vto provide a speciic arrangementfor a gun barrel in which the cooling inuence is extended to the ends ofthe barrel. l

To these and other ends, the invention consists in the construction,arrangement and combination of elements described hereinafter andpointed out in the claims forming a part of this specication.

A preferred embodiment of the invention illustratedin connection with agun barrel, is shown in the accompanying drawing, in which,

Fig. 1 is a longitudinal sectional view of the improved coolingapparatus applied to a gun barrel.

Figs. 2 and 3 `are sectional views on the corresponding lines of Fig. 1.

reference there is shown a support 5 which is -a part of the receiver ofa machine gun of the Browning type and which slidably mounts the rearend of a gun barrel 6. 'I'he support 5 carries a jacket comprising arear end plate 1 threaded on the support 5, a front end plate 8 having abearing 9 for receiving the muzzle end of the barrel, and an outercylinder I0 associated with the front and rearplates. 'I'he bearing 9pref- 4,5 erably carries anti-friction contact elements, specicallyballs Il, for engaging the gun barrel in rear of its muzzle.

Within the jacket and associated therewith are a rear header plate I2and a front header plate I3 spaced respectively from the rear end plate1 and front end plate 8 and establishing a rear chamber I4 and a frontchamber I5. For convenience in assembling the rear header plate I2 has aiiange I6 threaded to both the rear end plate 1 and the cylinder I0while the front header Referring to the drawing by characters of plate-I3 has a flange I'I threaded to the cylinder I0. The header platescarries a pair of concentric cylinders, the inner cylinder I8 beingspaced from the gun barrel to provide an annular chamber I9 and theintermediate cylinder 20 being preferably disposed closer to the outercylinder I9 and cooperating with the inner and outer cylinders torespectively provide an annular inner expansion chamber 2| and anannular outer expansion chamber 22.

A supply line ,23 including a cut-oli valve 24 is provided for admittinga gas, such as carbon dioxide, into the outer expansion chamber 22.Ports 25 in the rear header plate I2 enable the gas to flow into therear chamber I4 which has communication withthe chamber I9 by means of arestricted passage 26 which is convenientlyv provided by spacing theheader plate from the front face of the support 5. The inner cylinder I8is formed with small ports 2'I leading into the expansion chamber 2|.The front header plate which abuts or is secured to the bearing 9 isprovided with ports 28 for conducting gas from the expansion chamberinto the front chamber I5; and the front end plate has vents 29.

A tubular extension 3U is formed on the front end plate in prolongationof the bearing 9 and cooperates therewith in establishing an expansionchamber 3| for the gases of the propellent charge which issue from themuzzle of the barrel. This chamber contains a liner 32 within which aring 33 on the muzzle of the gun barrel is slidably received. When thegun barrel is in its normal in battery position its iront end isapproximately in line with the front end plate 8.

A plug 34 on the outer end of the liner and provided with a bulletopening 35 serves to baille a portion of the escaping gases of dischargeand to build up -pressure in thei expansion chamber 3| which acts on thefront -face of the barrel and Von the ring 33, and supplements the forceof recoil in moving the barrel rearwardly and insuring properfunctioning of the various parts of the machine gun.

WhenV the gun is being fired the barrel rapidly attains a temperaturewhich is greater than desired and whichinterferes with successfuloperation. In order to cool the ban'el, gas under pressure is admittedinto the outer expansion chamber 22 where it expands and thus has itstemperature lowered. The gas passes through the ports 25 into the rearchamber I4 and then through the restricted passage 26 to the annularchamber I9.

and into contact with the hot gun barrel. While in the chamber I9 thetemperature of the gas is raised and its pressure consequentlyincreased.

As the gas expands it passes through the small.

ports 2 into the cylinder I8 and enters the chamber 2l where itsexpansion results in a reduction of temperature. The gas in flowingtowards the ports 28 to bc relieved through the vents 29 tends to coolthe inner cylinder I8 and the intermediate cylinder 20 and the gascontained in the chambers I9, 2|, 22. The gas in the front chamber I5extends its cooling influence to the bearing 9, to the muzzle of thebarrel and to the liner 32 of the expansion chamber 3|. A portion of thegas flows past the balls Il and directly contacts the muzzle oi` thebarrel.

I claim:

1. In a gun, a support, a barrel mounted in the support and projectingtherefrom, a cooling apparatus for the barrel including an outer cyl;Yinder having a rear ond plate mounted on the support and a front endplate with a bearing for receiving the muzzle oi the barrel, rear andfronte header plates within thc outer cylinder and spaced from the rearand iront end plates to establish a rear and a front chamber, an innercylinder xed to the header plates and spaced from the barrel toestablish an annular chamber in communication with the rear chamber, anintermediate cylinder fixed to the header plates between the inner andouter cylinders and establishing therewith an inner and an outerexpansion chamber, ports in the rear header plates to establishcommunication between the outer expansion chamber and the rear chamber,ports in the inner cylinder, ports in the iront header plate toestablish communication between the inner expansion chamber and theiront chamber, means for ventingr the front chamberto atmosphere, andmeans for admitting a compressed gas to the outer expansion chamber.

2. In a cooling apparatus, a member to be cooled, an outer cylinderhaving rear and front end plates receiving the member to be cooled. rearand front header plates within the outer cylinder and spaced from therear and front end plates to establish a rear and a front chamber, aninner cylinder xed to the header plates and spaced from the member to becooled to establish an annular chamber, an intermediate cylinder fixedto the header plates between the inner and outer cylinders andestablishing therewith an inner and an outer expansion chamber, ports inthe rear header plate to establish communication between the outerexpansion chamber and the rear chamber, ports in the inner cylinder,ports in the front header plate to establish communication between theinner expansion chamber and the front chamber, means for venting thefront chamber to atmosphere, and means for admitting a compressed gas tothe outer expansion chamber.

3. In a cooling apparatusamember to becooled, a jacket surrounding themember to be cooled and including an inner cylinder spaced from themember to be cooled, an outer cylinder and an intermediate cylindercooperating with the inner and outer cylinders to establish respectivelyan .inner and an outer expansion chamber, means for admitting acompressed gas to the outer expansion chamber, means for conducting gasfrom the outer expansion chamber to the space between the inner cylinderand the member to be cooled, means for conducting:- gas from said spaceto theiv inner expansion chamber, and means for venting the innerexpansion chamber.

STEPHEN H. MACGREGOR.

